This invention relates generally to semiconductor integrated circuit packages and more particularly, to an improved power quad flat pack arrangement which provides an electrically enhanced integrated-circuit package structure.
As is generally known in the art, an integrated circuit is formed on a small, substantially planar, piece of semiconductor material such as silicon, known as a chip or integrated-circuit die. The integrated-circuit die generally contains a number of circuits therein and includes a plurality of bonding pads disposed on its top surface adjacent its peripheral edges. In a conventional quad flat pack (QFP) package assembly, the integrated-circuit die is mounted to a centrally-located die-attach paddle, or pad, of a thin metal lead frame which is typically stamped or chemically etched from strips of copper-containing materials. The die-attach paddle is rectangular in shape and is supported at each of its four corners by a radially extending support beam.
The lead frame includes a plurality of thin, closely-spaced conductive leads whose inner ends radially extend away from the edges of the die. The inner ends of the conductive leads are called bonding fingers. Very thin gold bonding-wires have their one ends bonded to the corresponding bonding pads on the integrated-circuit die and their other ends bonded to the corresponding bonding fingers. The entire assembly thus described is encapsulated in a molded plastic material so as to form a molded-plastic package body.
As advancements are made in semiconductor integrated-circuit of packaging and assembly technologies, the semiconductor integrated-circuit devices themselves are becoming smaller and smaller, which permits higher packing densities and faster speeds of operation. However, this has caused many manufacturing and processing problems, as well as associated increased cost of quad flat pack assemblies. For example, as the packing density becomes higher and higher, there is created a large amount of heat dissipation by the semiconductor integrated-circuit devices, which may cause a reduction in their overall performance, as well as possible damage or failure of the integrated-circuit devices themselves. In addition, as the operating speeds increase, the problems of inductance within the power conductions of an integrated-circuit and to associated power leads become significantly more important. These inductances within the integrated-circuit devices and in its associated leads may cause ground bounce noise, thereby degrading its high speed of performance.
Accordingly, there has arisen a need for improved power quad flat pack arrangement which has enhanced thermal characteristics. This is achieved in the present invention by the provision of a double-sided printed circuit board having VSS ground and VDD power planes disposed on its opposite surfaces and attached to appropriate power leads of a lead frame.